1. Field of the Invention
The present invention relates to a seal device for a guide device used for a moving portion of various machine tools, industrial robots or various common machines. Particularly, the present invention relates to a seal device for a guide device in which a slider striding over a rail is guided along the rail. More particularly, the present invention relates to a seal device which effectively exhibits a sealing function even in a guide device in which the rail width is partially different. The present invention also relates to a guide device in which the seal device is used.
2. Description of the Related Art
Conventionally, there is provided a seal device for a guide device shown in FIGS. 1(a) and 1(b). In the drawings, reference numeral 121 is referred to as an end seal attached to an end portion of the slider 120 arranged striding over the rail 130 and moved along the rail 130. This end seal 121 is composed in such a manner that a rubber member 124 is coated on a plate-shaped core metal 123. The core metal 123 has a recess portion 122 in which the rail 130 penetrates. A seal portion 125, which is called a lip, is formed at the inner circumferential edge of the recess portion 122. Since a forward end portion of the seal portion 125 closely comes into contact with the outer circumferential face of the rail 130 and moves together with the slider 120, foreign objects such as dust does not get into the slider 120. FIG. 1(a) is a front view of the slider 120 and end seal 121, and FIG. 1(b) is a sectional view of the inner circumferential portion of the end seal 121.
In the conventional seal device, the following problem may be encountered. The dimension t (interval between the inner circumferential face of the core metal 123 and the outer circumferential face of the rail 130) of the seal portion 125 of the end seal 121 is 1 to 2 mm. In case where the width of the rail 130 is different as shown in FIG. 2, for example, a transport device described in Japanese Unexamined Patent Publication No. 2001-99152 in which the slider 120 moves on the rail 130, the rail width of the curved portion 130B of the rail 130 is smaller than that of the straight portion 130A, it is impossible for the elastic extension and contraction of the seal portion 125 to absorb a change in the width of the rail 130. That is, it is impossible for the elastic extension and contraction of the seal portion 125 to absorb a reduction of the width in the small width portion. Therefore, the forward end portion of the seal portion 125 is separated from the outer circumferential face of the rail 130, which results in a defective sealing function.
In order to solve the above problem, Japanese Patent Publication No. 2939846 discloses a seal device as shown in FIG. 3. This seal device 110 includes a pair of end face plates 102, 103 made of metal arranged at the end portions of the slider 100 in the moving direction. The end face plates 102, 103 have an inside shape formed into the same profile as that of the outer face of the rail 101. A small gap is formed between the inside of the end face plates 102, 103 and the rail 101. The seal device further includes a support member 104 interposed between the end plates 102, 103; two side seal members 105, 106 and one upper seal member 107 made of bearing metal and arranged in a cut-out portion provided inside the support member 104. The two side seal members 105, 106 and one upper seal member 107 are formed in shapes that correspond to the profile of the outer face of the rail 101. The two side seal members 105, 106 and one upper seal member 107 are restricted to move by the pair of end face plates 102, 103. The seal device further includes compression springs 108 for elastically pushing the seal members 105, 106, 107 onto the outer face of the rail 101.
However, even in the seal device 110 composed as described above, the following problems may be encountered. In case where the slider 100 is guided along the rail 101 in which a straight portion and curved portion are continuously connected with each other, a gap is caused between the rail 101 and the side seal members 105, 106 by an inner wheel difference of the curved portion, which deteriorates the sealing function of the seal member. Further, since the seal member is divided into three pieces of the side seal members 105, 106 and the upper seal member 107 so that the seal members do not come into contact with each other, a gap is caused at each of the intersections (opposing faces) of the divided seal members. Further, in case where the inner wheel difference is caused in the curved portion of the rail 101, it is impossible to absorb the inner wheel difference. Further, this device is disadvantageous in that the number of parts is large and the structure becomes complicated. For example, when such a structure is adopted that the divided seal members come into contact with each other, a gap is formed by the abrasion caused between the divided seal members.
In the conventional-guide device, the end seal 121 is arranged at the end of the slider 120, and the seal device 110 is arranged at the end of the moving member (slider) 100 as described above. However, no seal devices are arranged in the side portions of the slider 120 and the moving member (slider) 100, that is, no seal devices are arranged in the portions opposed to the side of the rail 130. Therefore, problems may be encountered in which dust gets into the slider from the side portion. Therefore, it is impossible to apply the conventional guide device, for example, to a wood working machine used in a dusty place.